Cone-shaped Pattern Research Articles

Monitoring Air Sparging Using Resistivity Tomography

AbstractAir sparging is a relatively new technique for the remediation of ground water contaminated with petroleum hydrocarbons. In this technique, air is injected below the water table, beneath the contaminated soil. Remediation occurs by a combination of contaminant partitioning into the vapor phase and enhanced biodegradation. The air is usually removed by vacuum extraction in the vadose zone.The efficiency of remediation from air sparging is a function of the air flow pattern, although the distribution of the injected air is still poorly understood. Cross‐borehole resistivity surveys were performed at a former service station in Florence, Oregon, to address this unknown. The resistivity measurements were made using six wells, one of which was the sparge well. Data were collected over a two‐week period during and after several air injections, or sparge events. Resistivity images were calculated between wells using an algorithm that assumes axially symmetric structures. The movement of the injected air through time was defined by regions of large increases in resistivity, greater than 100 percent from the background. During early sparge times, air moved outward and upward from the injection point as it ascended to the unsaturated zone. At later sparge times, the air flow reached a somewhat stable cone‐shaped pattern radiating out and up from the injection point. Two days after sparging was discontinued, a residue of entrained air remained in the saturated zone, as indicated by a zone of 60 to 80 percent water saturation.

Air-Assist System for an Electrodynamic Sprayer

ABSTRACTTHE Electrodyn spraying device, utilizing electro-dynamic principles, was introduced in England in the late 1970's. A major problem with the system has been poor penetration into a tall, dense plant canopy. An air-assist unit (utilizing rapidly moving air to accelerate spray droplets emanating from the Electrodyn) was designed to aid plant canopy penetration and increase spray deposition. The air assist system requires less than 0.56 kW/ nozzle of air power to operate and results in minimal cost addition to the system. The air-assist unit substantially increased the spray droplet velocity without seriously affecting droplet size. Fluorometric tracing of the spray into a 10-cm tall cover of large crabgrass was used to examine plant canopy penetration. A wide or intermediate cone-shaped air pattern provided increased spray droplet penetration into the plant canopy when compared to the original electrodynamic sprayer and hydrualic nozzles. With a narrow cone setting, the system increased total chemical deposition over fan hydraulic nozzles by 56%..